Instruments · Chronometer
Chronometer by Harrison & Son, England, 1770
- Maker / attribution
- Harrison & Son (maker); Harrison and Son (maker)
- Date
- 1770
- Historical period
- Precision & Scientific Horology (1750 – 1850)
- Country of origin
- England
- Place
- London, Greater London, England, United Kingdom, London
- Object type
- Chronometer
- Holding institution
- Science Museum Group, London
- Accession / object no.
- L2015-3480
- Credit line
- Lent by the Worshipful Company of Clockmakers
- Catalogue title (original)
- Marine Timekeeper known as 'H5' by John Harrison and Son 1770
Record summary
Held and catalogued by Science Museum Group, London (object number L2015-3480), this is a chronometer by Harrison & Son, made in London, Greater London, England, United Kingdom, London, dated 1770. The Atlas places it in the Precision & Scientific Horology period (1750 – 1850) of its Instruments collection. The record is illustrated with 4 photographs.
Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.
Catalogue description
Science Museum Group description
Mechanically, this timekeeper is very similar to that of John Harrison's prize-winning longitude watch, H4 (in the collections of the Royal Museums Greenwich). It is now generally known as H5, being the fifth and last timekeeper that he produced as part of the 'Longitude Reward', and completed when he was 77. Personally tested by King George III at his observatory in Richmond, this timekeeper helped secure Harrison the last part of his Longitude prize-money. Clockmakers Museum No. 598
Historical context
Precision & Scientific Horology (1750 – 1850)
Harrison solves longitude; Mudge invents the lever; Breguet's Paris workshop defines the modern watch.
The longitude problem was solved by the marine chronometer and lunar distance methods; dividing engines made precision scales possible, and observatories set time by transit instruments.
Read the period in the timelineMore instruments from this periodEarlier: Early Modern Horology
Atlas type guide
Chronographs and split-seconds watches
A chronograph is a watch with an additional seconds hand that can be started, stopped and returned to zero independently of the timekeeping. Louis Moinet built an early example in 1816 and Nicolas Rieussec a recording 'chronographe' in 1821; Adolphe Nicole's heart-shaped reset cam (patented 1862) made the modern return-to-zero possible. Split-seconds (rattrapante) chronographs add a second hand that can be stopped for intermediate times; flyback chronographs restart instantly.
Chronographs were essential tools for doctors (pulsometer scales), artillery (telemeter), engineers and sport. In wristwatches, Valjoux, Venus, Lemania and later the automatic chronographs of 1969 (Zenith El Primero, the Chronomatic Calibre 11 group and Seiko 6139) are milestones.
What to look for
- Push-pieces on the case band or a single button in the crown (monopusher).
- Subsidiary registers for minutes and hours; tachymeter, telemeter or pulsometer scales.
- Column wheel versus cam control visible in the movement.
- Calibre markings of specialist makers (Valjoux, Lemania, Venus, Landeron).
Dating clues
- Pocket chronographs with heart cam reset: after 1862.
- Wrist chronographs: from c. 1910; two-button designs from the 1930s.
- Automatic chronographs: from 1969.
General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.
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